You show the registry key, but not the script. What does it do? Which "Trusted Source" did you get it from?
Why do you want to change permissions through the registry? It is not something I would attempt, especially (but not limited to) permissions. A wrong move there and you lock the system down period.
Mark
I have the following script to change the permission of USB:
\REGISTRY\MACHINE\SYSTEM\CurrentControlSet\Enum\USB [7]
Even after executing this the entry that I require is not deleted.

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